Energy recovery system for a semiconductor fabrication facility

ABSTRACT

One illustrative energy recovery system disclosed herein includes a semiconductor fabrication facility (“fab”) and a closed chilled water loop including a chilled water stream delivered to the fab and a returning water stream that is received from the fab. In this example, the system also includes a primary heat exchanger having a first fluid side and a second fluid side, the first fluid side is adapted to receive supply water and the second fluid side is adapted to receive at least a portion of the returning return water stream, wherein the primary heat exchanger is adapted to effectuate heat transfer between the supply water flowing in the first fluid side and the returning water stream flowing in the second fluid side.

BACKGROUND Field of the Disclosure

Generally, the present disclosure relates to various illustrativeembodiments of a novel energy recovery system for a semiconductorfabrication facility.

Description of the Related Art

Integrated circuit (IC) products, e.g., computer chips, are fabricatedin a semiconductor fabrication facility (“fab”). Modern semiconductorfabrication facilities typically occupy a relatively large land area andcontain many climate-controlled buildings that house many processingtools that are operated by thousands of employees to manufacture ICproducts. A fab typically includes various mechanical systems to providenecessary utilities, e.g., heating, ventilation, water, airconditioning, piping, etc., to the fab to operate the processing toolsand maintain the internal environment within the fab. In general, theoperation of a modern semiconductor fabrication facility results in theconsumption of an enormous amount of resources, e.g., electrical power,water, etc., all at great cost to the semiconductor fabricationfacility. Manufacturers of IC products are under constant pressure toreduce operating costs so that their products remain competitivelypriced in the highly competitive market for IC products.

The present disclosure is directed to various illustrative embodimentsof a novel energy recovery system for a semiconductor fabricationfacility.

SUMMARY

The following presents a simplified summary of at least one disclosedembodiment in order to provide a basic understanding of some aspects ofthe subject matter disclosed herein. This summary is not an exhaustiveoverview of all of the subject matter disclosed herein. It is notintended to identify key or critical elements of the subject matterdisclosed herein or to delineate the scope of any claims directed to anyof the subject matter disclosed herein. Its sole purpose is to presentsome concepts in a simplified form as a prelude to the more detaileddescription that is discussed later in the application.

The present disclosure is generally directed to various illustrativeembodiments of a novel energy recovery system for a semiconductorfabrication facility. One illustrative system disclosed herein includesa semiconductor fabrication facility (“fab”) and a closed chilled waterloop comprising a chilled water stream delivered to the fab and areturning water stream that is received from the fab. In this example,the system also includes a primary heat exchanger having a first fluidside and a second fluid side, the first fluid side is adapted to receivesupply water, the second fluid side is adapted to receive at least aportion of the returning water stream, wherein the primary heatexchanger is adapted to effectuate heat transfer between the supplywater flowing in the first fluid side and the returning water streamflowing in the second fluid side.

Yet another illustrative novel system disclosed herein includes asemiconductor fabrication facility (“fab”), a plurality of water-cooledprocessing tools positioned within the fab and a closed process coolingwater loop that is dedicated to supplying chilled water to the pluralityof water-cooled processing tools, wherein the process cooling water loopincludes a chilled water stream delivered to the fab that flows to theplurality of water-cooled processing tools and a returning water streamis received from the plurality of water-cooled processing tools. In thisexample, the system also includes a primary heat exchanger having afirst fluid side and a second fluid side, wherein the first fluid sideis adapted to receive supply water supplied from a municipality and thesecond fluid side is adapted to receive at least a portion of thereturning water stream, wherein the primary heat exchanger is adapted toincrease a temperature of the supply water flowing in the first fluidside and decrease a temperature of the returning water stream flowing inthe second fluid side

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may be understood by reference to the followingdescription taken in conjunction with the accompanying drawings, inwhich like reference numerals identify like elements, and in which:

FIG. 1 depicts one illustrative embodiment of a novel energy recoverysystem disclosed herein for a semiconductor fabrication facility.

While the subject matter disclosed herein is susceptible to variousmodifications and alternative forms, specific embodiments thereof havebeen shown by way of example in the drawings and are herein described indetail. It should be understood, however, that the description herein ofspecific embodiments is not intended to limit the invention to theparticular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION

Various illustrative embodiments are described below. In the interest ofclarity, not all features of an actual implementation are described inthis specification. It will of course be appreciated that in thedevelopment of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthis disclosure.

The present disclosure will now be described with reference to theattached FIGURES. Various structures, systems and devices areschematically depicted in the drawings for purposes of explanation onlyand so as to not obscure the present disclosure with details which arewell known to those skilled in the art. The words and phrases usedherein should be understood and interpreted to have a meaning consistentwith the understanding of those words and phrases by those skilled inthe relevant art. No special definition of a term or phrase, i.e., adefinition that is different from the ordinary or customary meaning asunderstood by those skilled in the art, is intended to be implied byconsistent usage of the term or phrase herein. To the extent that a termor phrase is intended to have a special meaning, i.e., a meaning otherthan that understood by skilled artisans, such a special definitionshall be expressively set forth in the specification in a definitionalmanner that directly and unequivocally provides the special definitionfor the term or phrase.

As will be readily apparent to those skilled in the art upon a completereading of the present application, the methods and systems disclosedherein may be employed in manufacturing a variety of different ICproducts and devices, including, but not limited to, logic devices,memory devices, etc. Of course, the inventions disclosed herein shouldnot be considered to be limited to the illustrative examples depictedand described herein. With reference to the attached FIGURES, variousillustrative embodiments of the methods and systems disclosed hereinwill now be described in more detail.

FIG. 1 depicts one illustrative embodiment of a novel energy recoverysystem 100 disclosed herein for a semiconductor fabrication facility 10(“fab”) as well as portions of a facility support system that provides,or supports the provision of, various utilities to the fab 10. Thesemiconductor fabrication facility 10 depicted in FIG. 1 is intended tobe representative in nature of one or more buildings that are part ofthe fab 10. The fab 10 maybe adapted to form any of a variety ofdifferent types or forms of IC products or it may be dedicated to theformation of only a single type of IC product, e.g., DRAM memorydevices.

As noted above, the fab 10 may include many processing tools (not shown)that are adapted to perform many different processing operationscommonly employed in the fabrication of IC products, e.g., depositiontools for performing various deposition processes (e.g., chemical vapordeposition (CVD), atomic layer deposition (ALD), etc.), furnaces forperforming thermal growth processes and/or general heating operations,ion implantation tools, photolithography tools, inspection tools,packaging tools, etc. Many of these processing tools must be cooled bychilled cooling water that is delivered to the fab and ultimatelysupplied directly to the tools so as to insure that the temperature ofthe tools remains within a desired range. The fab 10 also typicallyincludes large and complex computer systems to operate the various toolsand systems within the fab. Typically, hundreds or thousands ofindividuals may be working within the fab 10 on a daily basis.

The processing tools, systems and people within a typical fab 10generate an enormous amount of heat, i.e., a heat load, that must beremoved from the fab 10 so as to maintain the processing tools at thedesired temperature and maintain the internal environment of the cleanroom(s) within the fab 10 at the desired temperature and humiditylevels. Thus, the cooling system(s) that is employed to maintain theinternal environment within the fab 10 as well as the operationaltemperature of the processing tools is important to the successfuloperation of the fab 10.

A modern semiconductor fabrication facility uses cooled or chilled waterproduced by a chilled water plant for a variety of purposes. Forexample, the chilled water plant (not shown) may supply many differentstreams of chilled water to the fab 10 via various closed chilled waterloops. These different closed loops of cooling water may be at differenttemperatures and the flow rate of the chilled or cooled water in each ofthe closed loops may also be different. In one illustrative embodiment,the chilled water plant may supply two primary loops of chilled water tothe fab 10: a medium temperature loop (MT loop) and a relatively coolerlow temperature loop (LT loop). In one illustrative example, the MT loopmay deliver a chilled water stream to the fab 10 at a temperature ofabout 51° F. which returns from the fab 10 at a temperature of about 61°F. On the other hand, the cooler LT loop may deliver a chilled waterstream to the fab 10 at a temperature of about 41° F. which returns fromthe fab 10 at a temperature of about 51° F.

As will be appreciated by those skilled in the art after a completereading of the present application, heat will be recovered from thereturning water stream of one of the closed water loops that servicesthe fab 10 so as to heat water received by the fab 10 (and perhapsstored at the fab 10) from a municipality. The returning water stream ofany closed loop of cooling water that supports the fab 10 may be usedfor this purpose, as long it is of sufficient temperature to perform theheat transfer operations disclosed below. Typically, the closed waterloop with the highest temperature returning water stream will be used asit typically will be the most efficient in terms of heat transfer, but,in some cases, another closed water loop with a cooler returning waterstream may be used to provide the desired heat transfer as more fullyexplained below.

Most modern fabrication facilities 10 have a dedicated chilled waterloop—typically referred as the process cooling water loop—that is usedonly to cool the processing tools in the fab 10. Another dedicatedchilled water loop can be used to cool the internal environment of theclean room in the fab 10 by circulating chilled water through coilslocated in various air handling units and return air chases (not shown)in the fab 10. This later chilled water loop may also be used for otherpurposes as well. In the example discussed below, heat from thereturning water stream of the process cooling water loop—the loopdedicated to the cooling of the processing tools—will be used to heatthe city water supplied to or stored at the fab 10. However, as shouldbe clear from the foregoing, the presently disclosed inventions shouldnot be considered to be limited to only situations where the processcooling water loop is used for the purposes disclosed herein, as anyclosed chilled water loop may be used depending upon the particularapplication. Moreover, when it is stated herein that a closed chilledwater loop comprises a chilled water stream delivered to the fab or areturn water stream received from the fab, such language should beunderstood to cover situations where the chilled water in chilled loopis used for any purpose, e.g., the chilled water loop may be a processcooling water loop that is dedicated to supplying cooling water to aplurality of water-cooled processing tools within the fab 10 or to achilled water loop that supplies chilled water to the fab 10 forpurposes of cooling the ambient air within the clean room(s) within thefab via use of various air handling units.

As discussed above and with reference to FIG. 1, in one illustrativeembodiment of a fab 10 disclosed herein, the support system for the fab10 includes a closed loop cooling system whereby a relatively cooler(and representative) chilled process cooling water stream is deliveredto the fab 10 via line 16 and a relatively warmer (and representative)process cooling return water stream exits the fab 10 via line 18.Although only a single process cooling water line 16 is depicted in thedrawing, in actual practice, the single process cooling water line 16may be split into multiple steams of process cooling water that enterthe fab 10 at various locations. Similarly, although only a singleprocess cooling water return line 18 is depicted in the drawing, inactual practice, the single process cooling water return stream may besplit into multiple steams of return process cooling water that exit thefab 10 at various locations. As noted above, in this illustrativeexample, the closed process cooling water loop is dedicated to coolingthe processing tools within the fab 10.

As will be appreciated by those skilled in the art after a completereading of the present application, the heat load of the water-cooledprocessing tools within the fab 10 will be transferred to the chilledprocess cooling water stream as the chilled process cooling water streamis circulated through the various processing tools within the fab 10.After absorbing the heat load of the processing tools, the previouslychilled process cooling water stream that was delivered to the fab 10via line 16 exits the fab 10 as the relatively warmer returning processcooling water stream via line 18. The system 100 includes various valves(not shown), e.g., control valves, isolation valves, etc., controlsensors (not shown), e.g., pressure, temperature and flow rate sensors,etc., and pumps (some of which are not shown) so as to route variousfluids to desired locations and equipment within the system as describedmore fully below. The manner in which such equipment, sensors and valvesare arranged, monitored and operated so as to effectuate the desiredrouting of various fluid streams is well known to those skilled in theart and will not be described in any detail.

Supply water is supplied to the facilities or support system of the fab10 via a representative incoming supply water line 12. The supply wateris typically supplied by a local municipality, e.g., a city, and it istypically potable water that is suitable for human consumption. However,the presently disclosed subject matter should not be considered aslimited to only situations where the supply water to the system 100 issupplied by a municipality. In one illustrative embodiment, the supportsystem also includes one or more water storage tanks 14 that are adaptedto store relatively large quantities of the supply water. The storagetanks 14 are typically provided proximate the location of the fab 10 soas to insure that water can be supplied to the fab 10 even in the eventof an interruption in the supply of the supply water from themunicipality. Supply water may be taken from the storage tanks 14 on anas needed basis. In this embodiment, the support system also includesone or more pump water storage tanks 14A that will be used for purposesdescribed more fully below.

As will be appreciated by those skilled in the art, manufacturing of ICproducts typically requires the consumption of significant amounts ofhighly purified water, e.g., deionized (or ultra-pure) water. Forpurposes of the following discussion, and as used in the claims, suchpurified water will be referred to deionized water. In the illustrativeexample of the support system depicted herein, deionized water issupplied to the fab 10 via line 34. The supply water is processed in asimplistically and schematically depicted deionized water system 33 soas to produce the deionized water. In the depicted example, thedeionized water system 33 is physically located outside of the fab 10,but that may not be the case in all situations. Such deionized watersystems 33 are commercially available and the components and operationof such deionization (purification) systems are well known to thoseskilled in the art. For example, such deionization systems may includevarious components or subsystems that perform various functions, e.g.,filtration, reverse osmosis, degasification, electro-deionization, etc.The deionized water that is delivered to the fab 10 typically must meetvery strict guidelines in terms of its characteristics and qualities,e.g., there are typically limits on the allowable amounts of entrainedparticulate matter, total organic carbon (TOC), dissolvedoxygen/nitrogen, etc., in the deionized water, as well as the electricalconductivity of the deionized water.

In general, the production of deionized water requires the temperatureof the supply water that is going to be deionized to be very tightlycontrolled. For example, in one illustrative embodiment, the supplywater that enters the deionized water system 33 via line 27 needs to beat a relatively precise temperature, e.g., 70° F.±1°. Also depicted inFIG. 1 are a representative secondary heat exchanger 32 and asimplistically depicted pump 15 that is positioned between the pumpwater storage tank(s) 14A and the secondary heat exchanger 32. Inpractice, the support system may include one secondary heat exchangerfor heating the supply water (when the supply water is below 70° F.) andanother secondary heat exchanger for cooling the supply water (when thesupply water is above 70° F.). Thus, the purpose of the secondary heatexchanger(s) 32 is to insure that the supply water that exits thesecondary heat exchanger 32 at line 27 is at the desired temperature,e.g., 70° F.±1°, before it enters the deionized water system 33. Thesefinal temperature adjustments are sometimes called trim temperaturecontrol and the energy sources are paid heating/cooling rather than freeor recovered energy.

A crossing heat transfer fluid enters the secondary heat exchanger 32via line 29 and exits the secondary heat exchanger 32 via line 31. Inthe case where the secondary heat exchanger 32 is used to heat thesupply water entering via line 25, the temperature of the heat transferfluid in line 29 will be greater than the temperature of the heattransfer fluid in line 31 after it exits the secondary heat exchanger32. The opposite situation would be present in the case where thesecondary heat exchanger 32 is used to cool the supply water that entersthe secondary heat exchanger 32 via line 25, i.e., the temperature ofthe heat transfer fluid in line 29 will be less than the temperature ofthe heat transfer fluid in line 31 after it exits the secondary heatexchanger 32. The secondary heat exchanger 32 may take a variety offorms, e.g., a shell and tube heat exchanger, a plate and frame heatexchanger, etc. In many applications, the secondary heat exchanger(s) 32may actually be an integral part or a subsystem of the deionized watersystem 33.

Also depicted in FIG. 1 is a primary heat exchanger 20 andsimplistically depicted pumps 22 and 39. The primary heat exchanger 20may take a variety of forms, e.g., a shell and tube heat exchanger, aplate and frame heat exchanger, etc. The primary heat exchanger 20 has afirst fluid side 20A and a second fluid side 20B. In general, in oneillustrative embodiment, substantially all of the incoming supply waterflow in line 12X will be modulated via one or more variable speed drive(VFD) pumps to the side-stream loop 40 where it will be circulatedthrough the first fluid side 20A of the primary heat exchanger 20 whilethe returning process cooling water stream in line 18 will be directedto a side-stream loop 42 where it will be modulated via one or morevariable speed drive (VFD) pumps through the second fluid side 20B ofthe primary heat exchanger 20, so as to effectuate heat transfer betweenthe supply water stream in the first fluid side 20A and the returningprocess cooling water stream in the second fluid side 20B. In oneillustrative embodiment, as described more fully below, when thetemperature of the supply water stream (in line 12X) to be introducedinto the first fluid side 20A is less than the temperature of thereturning process cooling water stream (in line 18) to be introducedinto the second fluid side 20B, the energy recovery system 100 harveststhe available free energy, i.e., the available heat in the returningprocess cooling water stream (in line 18), to heat the supply water(from line 12X) by modulating the flow of the supply water stream andthe returning process cooling water stream. As a result of thistemperature differential, the returning process cooling water stream inthe second fluid side 20B effectively increases the temperature (i.e.,warms) the supply water flowing through the first fluid side 20A of theprimary heat exchanger 20.

In the following discussion, it is assumed that the supply water in line12X is at a temperature that is less than the temperature of thereturning process cooling water stream in line 18. With respect to theside-stream loop 40 of the incoming supply water, in one illustrativeembodiment, substantially all of the relatively cooler supply water inline 12X (from the storage tank(s) or directly from the water line 12)enters the primary heat exchanger 20 via line 13 where its temperatureis increased, and it exits the primary heat exchanger 20 via line 17 asa heated supply water stream driven by the VFD pump 22. The heatedsupply water stream then exits the pump 22 via line 19 where it flows(via line 21) to the pump water storage tank 14A.

With respect to the side-stream loop 42 of the relatively warmerreturning process cooling water stream in line 18, at least a portion ofthe relatively warmer returning process cooling water stream in line 18enters the second fluid side 20B of the primary heat exchanger 20 vialine 31 and exits the primary heat exchanger 20 via line 35 as a cooledreturning process cooling water stream driven by the VFD pump 39. Thiscooled returning process cooling water stream exits the pump 39 and thenre-combines with the relatively warmer returning process cooling waterstream in line 18 and flows (via line 37) to a plurality ofsimplistically depicted VFD pumps 24 that are arranged in anillustrative parallel configuration. In turn, the output of the pumps 24is supplied to one or more heat exchangers 26, e.g., shell and tube heatexchangers or plate/frame heat exchangers. The chilled water plant (notshown) supplies chilled water via another closed chilled water loop tocool the returning process cooling water that exits the pumps via heattransfer in the heat exchangers 26. In one illustrative example, chilledwater at a temperature of about 51° F. may be supplied to the heatexchangers 26 via line 28 and return to the chilled water plant via line30 after it has cooled the returning process cooling water flowingthrough the heat exchangers 26. As a result, the returning processcooling water that enters the heat exchangers 26 (via pumps 24) iscooled and exits the heat exchangers 26 as the chilled process coolingwater stream that is thereafter again delivered to the fab 10 via line16.

As will be appreciated by those skilled in the art after a completereading of the present application, in this illustrative example, theinclusion of the primary heat exchanger 20 in the energy recovery system100 permits at least a portion of the relatively warmer returningprocess cooling water stream in line 18 to be used to heat a portion ofthe relatively cooler supply water that is initially supplied to orstored at the support system. Using this approach, the primary heatexchanger 20 may be used to increase the temperature of the supply waterthat ultimately enters the secondary heat exchanger 32 via line 25,thereby reducing the amount of heating that needs to be supplied by thesecondary heat exchanger 32 to insure that the supply water in line 27(that exits the secondary heat exchanger 32) is at the desiredtemperature, e.g., 70° F.±1°, for introduction into the deionized watersystem 33. From an overall perspective, since the temperature of therelatively warmer returning process cooling water stream in line 18 willultimately be cooled in the heat exchangers 26 to the desiredtemperature of the chilled process cooling water stream delivered to thefab 10 via line 16, the portion of the relatively warmer returningprocess cooling water stream in line 18 that is diverted to and cooledin the primary heat exchanger 20 (to warm the incoming supply water onthe first fluid side 20A) is effectively free energy that can be put toa useful purpose. Moreover, the cooling of the portion of the relativelywarmer returning process cooling water stream in line 18 that flowsthrough the second fluid side 20B of the primary heat exchanger 20effectively reduces the heat load that must be removed by the heatexchangers 26 and ultimately the chilled water plant, thereby reducingoperating costs.

Of course, the efficiency and heat transfer capabilities of the energyrecovery system 100 may depend upon a variety of factors, e.g., theenvironmental temperature conditions at the location of the fab 10, theheat load from the processing tools within the fab 10, the temperatureof the supply water that is supplied to the support system (via line 12or via the tank(s) 14), the temperature and flow rate of the chilledprocess cooling water stream, the temperature and flow rate of thereturning process cooling water stream and/or the desired temperatureand flow rate of the water that enters the deionized water system 33 viathe line 27.

By way of example only, in one illustrative embodiment, the fab 10 maybe in a locale such that the average temperature of the supply water(from line 12 or the tank(s) 14) may be about 36° F. during the winterand about 75° F. in the summer. Moreover, based upon the heat load ofthe processing tools within the fab 10, the chilled process coolingwater stream delivered to the fab 10 via line 16 may need to be at atemperature of about 59° F., while the relatively warmer returningprocess cooling water stream in line 18 may be at a temperature of about68° F. In this example, the temperature of the supply water in line 27after it exits the secondary heat exchanger 32 will have a target valueof 70° F.±1°.

Based upon the above illustrative conditions, the flow of the variousstreams of water in the energy recovery system 100 during winterconditions will now be described. As noted above, various sensors andvalves will be deployed throughout the support system to providefeedback as to the temperature, pressure and flow rate of various waterstreams throughout the energy recovery system 100 so as to permitoperators to achieve the desired energy transfer effects describedbelow. In one illustrative example, with respect to the side-stream loop40, all of the relatively cooler supply water in line 12X, at atemperature of about 36° F. during winter conditions, enters the firstfluid side 20A of the primary heat exchanger 20 via line 13 and exitsthe primary heat exchanger 20 via line 17 at a temperature of about 65°F. as driven by the pump 22 and ultimately flows to the pump waterstorage tank 14A. This heated 65° F. supply water is then pumped (viapump 15) to the secondary heat exchanger 32 where it will be trim heated(via heat transfer with the heat transfer fluid flowing through thesecondary heat exchanger 32 in lines 29 and 31) to the desiredtemperature of 70° F.±1°. At that point, this heated water then flowsout of the secondary heat exchanger 32 via line 27 and is introducedinto the deionized water system 33 such that deionized water may bedelivered to the fab 10 via line 34.

Continuing with this illustrative example discussed above, with respectto the side-stream loop 42 of the relatively warmer returning processcooling water stream in line 18, at least a portion of the relativelywarmer returning process cooling water stream in line 18 enters thesecond fluid side 20B of the primary heat exchanger 20 via line 31 at atemperature of about 68° F. and exits the second fluid side 20B of theprimary heat exchanger 20 via line 35 as a relatively cooler returningprocess cooling water stream at a temperature of about 65° F. and flowsto the inlet of pump 39. This fluid then exits the pump 39 where it thenre-combines with the returning process cooling water stream in line 18and flows via line 37 to the pumps 24. In turn, the returning processcooling water stream that exits the pumps 24 is supplied to one or moreheat exchangers 26. Chilled water from the chilled water plant entersthe heat exchangers 26 via line 28 at a temperature of about 51° F. andreturns to the chilled water plant via line 30 at a temperature of about58° F. As a result, the returning process cooling water stream thatenters the heat exchangers 26 (via pumps 24) is cooled and exits theheat exchangers 26 as the chilled process cooling water stream at atemperature of about 59° F. which is then again delivered to the fab 10via line 16. As will be appreciated by those skilled in the art after acomplete reading of the present application, in this particular example,the primary heat exchanger 20 permits the heat energy in the returningprocess cooling water stream to be used to increase the temperature ofthe supply water flowing in the first fluid side 20A of the primary heatexchanger from about 36° F. to about 65° F. In turn, the heating of thesupply water in the primary heat exchanger 20 decreases the heat load ofthe secondary heat exchanger 32, i.e., it decreases the amount ofheating of the supply water that is required to be performed by thesecondary heat exchanger 32. More specifically, by heating the supplywater in the primary heat exchanger 20, the secondary heat exchanger 32only has to increase the water temperature of the supply water by about5° F. (from 65° F. to 70° F.). In contrast, if the relatively coldincoming supply water in line 12X (from line 12 or the tank(s) 14), at atemperature of about 36° F., was supplied directly to the secondary heatexchanger 32, then the secondary heat exchanger 32 would have toincrease the temperature of the supply water by about 34° F. to insurethat the supply water exiting the secondary heat exchanger 32 via line27 would have the desired temperature of about 70° F.±1°. Thus, by usingthe energy (i.e., heat) present in the returning process cooling waterstream (in line 18) to heat the supply water flowing through the firstfluid side 20A of the primary heat exchanger 20, significant energysavings may be obtained as it relates to the operation of the fab 10. Ineffect, the secondary heat exchanger 32 may be used to supply the lastfew degrees of heating (trim) of the supply water prior to the supplywater being introduced into the deionizing water system 33, i.e., thesecondary heat exchanger 32 may be used to fine tune the temperature ofthe supply water that exits via line 27.

Additionally, since the returning process cooling water stream (in line18) will eventually be cooled (via the heat exchangers 26) to thedesired temperature of the chilled process cooling water stream (in line16), the use of at least a portion of the heat energy within thereturning process cooling water stream is effectively “free” energy thatcan be put to the useful purpose described above. Additionally, as notedabove, by cooling a portion of the returning process cooling waterstream in the second fluid side 20B of the primary heat exchanger 20 (soas to heat the supply water in the first fluid side 20A of the primaryheat exchanger 20), the amount of cooling that must be performed by theheat exchangers 26 and ultimately the chilled water plant is alsoreduced, thereby resulting in additional cost savings.

The energy recovery system disclosed herein is environmentally friendlyin that it does not involve the use of water from a natural source ofwater, such as a lake or river, to achieve the heat transfer describedherein. When water is obtained from such natural sources of water, ittypically contains foreign matter, e.g., dirt, weeds, large particulatematter, etc., that must be removed to prevent fouling of various itemsof equipment through which the natural water flows. Such operations areinherently expensive and can result in significant down time.Additionally, in the case where water is discharged into such a naturalbody of water, care must be taken to insure that water is in fullcompliance with many regulations directed to the discharge of water froman industrial plant, all of which cost time and money.

The above discussion was directed to the use of the primary heatexchanger 20 under anticipated conditions during the winter. During theanticipated conditions during the summer, e.g., with supply water atabout 75° F., the supply water will need to be cooled to reach thedesired temperature of about 70° F.±1° prior to the introduction of thesupply water into the deionized water system 33. As noted above, thesystem may include a separate secondary heat exchanger 32 that isdedicated to cooling the supply water prior to it entering the deionizedwater system 33. However, under these conditions, there is only arelatively small temperature differential of about 7° F. between theincoming supply water (75° F.) that is supplied to the first fluid side20A of the primary heat exchanger 20 and the returning process coolingwater stream in line 18 (at a temperature of about 68° F.) that issupplied to the second side 20B of the primary heat exchanger 20. As aresult of this relatively small temperature differential, heat transferbetween the two water streams in the primary heat exchanger 20 may belimited or at best highly inefficient. In some situations, in may not beeconomically viable to circulate the supply water stream and thereturning process cooling water stream through the primary heatexchanger 20 under these conditions. Thus, the energy recovery system100 provides the operator with the ability to allow both the incomingsupply water stream (in line 12X) and the returning process coolingwater stream (in line 18) to simply bypass the primary heat exchanger 20in appropriate situations. In such a bypass situation, the supply water(at a temperature of about 75° F.) would be cooled to the desiredtemperature of about 70° F.±1° in the secondary heat exchanger 32 priorto introduction to the deionized water system 33. Thus, as will beappreciated by those skilled in the art after a complete reading of thepresent application, the energy recovery system 100 provides operatorswith great flexibility in terms of regulating the flow of variousstreams of fluid within the energy recovery system 100 so as to achievethe desired heat transfer results based upon the particular operatingconditions present at a particular fab 10 and any particular point intime throughout the year. For example, in the illustrative exampledepicted above, it may not be economically viable to use the primaryheat exchanger 20 during the peak months of summer, i.e., the primaryheat exchanger 20 may be simply bypassed during some months of the year.Of course, in other situations, the primary heat exchanger 20 may beused substantially year round. For example, if the fab 10 is located inan environment where the incoming supply water temperature in the summermonths is relatively cool, e.g., 50-60° F., then the returning processcooling water stream (in line 18) may be used to heat all or a portionof the supply water (in line 12X) in the summer months as well as thewinter months, i.e., on a year round basis.

As will be appreciated by those skilled in the art after a completereading of the present application, there are various novel systems andmethods disclosed herein. In one illustrative embodiment, a novel energyrecovery system disclosed herein includes a semiconductor fabricationfacility (“fab”) 10 and a closed chilled water loop having a chilledwater stream 16 delivered to the fab and a returning water stream 18that is received from the fab. In this example, the system also includesa primary heat exchanger 20 having a first fluid side 20A and a secondfluid side 20B, the first fluid side 20A is adapted to receive supplywater, and the second fluid side 20 is adapted to receive at least aportion of the returning water stream 18, wherein the primary heatexchanger 20 is adapted to effectuate heat transfer between the supplywater flowing in the first fluid side 20A and the returning water streamflowing in the second fluid side 20B.

Yet another novel energy recovery system disclosed herein includes asemiconductor fabrication facility (“fab”) 10, a plurality ofwater-cooled processing tools positioned within the fab and a closedprocess cooling water loop that is dedicated to supplying chilled waterto the plurality of water-cooled processing tools, wherein the processcooling water loop includes a chilled water stream delivered to the fabthat flows to the plurality of water-cooled processing tools and areturning water stream is received from the plurality of water-cooledprocessing tools. In this example, the system also includes a primaryheat exchanger 20 having a first fluid side 20A and a second fluid side20B, wherein the first fluid side 20A is adapted to receive supply waterreceived from a municipality and the second fluid side 20B is adapted toreceive at least a portion of the returning water stream 18, wherein theprimary heat exchanger 20 is adapted to increase a temperature of thesupply water flowing in the first fluid side 20A and decrease atemperature of the returning water stream flowing in the second fluidside 20B.

The particular embodiments disclosed above are illustrative only, as theinvention may be modified and practiced in different but equivalentmanners apparent to those skilled in the art having the benefit of theteachings herein. For example, the process steps set forth above may beperformed in a different order. Furthermore, no limitations are intendedto the details of construction or design herein shown, other than asdescribed in the claims below. It is therefore evident that theparticular embodiments disclosed above may be altered or modified andall such variations are considered within the scope and spirit of theinvention. Note that the use of terms, such as “first,” “second,”“third” or “fourth” to describe various processes or structures in thisspecification and in the attached claims is only used as a shorthandreference to such steps/structures and does not necessarily imply thatsuch steps/structures are performed/formed in that ordered sequence. Ofcourse, depending upon the exact claim language, an ordered sequence ofsuch processes may or may not be required. Accordingly, the protectionsought herein is as set forth in the claims below.

1. A system comprising: a semiconductor fabrication facility (“fab”); aclosed chilled water loop comprising a chilled water stream delivered tothe fab and a returning water stream that is received from the fab; anda primary heat exchanger comprising a first fluid side and a secondfluid side, the first fluid side being adapted to receive supply water,the second fluid side being adapted to receive at least a portion of thereturning water stream, wherein the primary heat exchanger is adapted toeffectuate heat transfer between the supply water flowing in the firstfluid side and the returning water stream flowing in the second fluidside.
 2. The system of claim 1, wherein the chilled water streamdelivered to the fab is at a first temperature where it enters the faband the returning water stream is at a second temperature where it exitsthe fab, wherein the first temperature is less than the secondtemperature.
 3. The system of claim 1, wherein the fab further comprisesa plurality of water-cooled processing tools, wherein the closed chilledwater loop is a process cooling water loop that is dedicated tosupplying chilled water to the plurality of water-cooled processingtools and wherein the returning water stream is received from theplurality of water-cooled processing tools.
 4. The system of claim 1,wherein the primary heat exchanger is adapted to increase a temperatureof the supply water flowing in the first fluid side and decrease atemperature of the returning water stream flowing in the second fluidside.
 5. The system of claim 4, wherein the supply water flowing in thefirst fluid side is at a first temperature where it enters the firstfluid side and the returning water stream flowing in the second fluidside is at a second temperature where it enters the second fluid side,wherein the first temperature is less than the second temperature. 6.The system of claim 1, wherein the primary heat exchanger is adapted todecrease a temperature of supply water flowing in the first fluid sideand increase a temperature of the returning water stream flowing in thesecond fluid side.
 7. The system of claim 6, wherein the supply waterflowing in the first fluid side is at a first temperature where itenters the first fluid side and the returning water stream flowing inthe second fluid side is at a second temperature where it enters thesecond fluid side, wherein the first temperature is greater than thesecond temperature.
 8. The system of claim 1, further comprising: anincoming water line in which the supply water is adapted to flow; and atleast one water storage tank that is adapted to receive supply waterfrom the incoming water line and store supply water, wherein the supplywater flowing in the first fluid side is received from at least one ofthe incoming water line or the at least one water storage tank.
 9. Thesystem of claim 1, further comprising a secondary heat exchanger that isadapted to receive the supply water after it exits the first fluid sideof the primary heat exchanger, wherein the secondary heat exchanger isadapted to increase a temperature of the supply water as it flowsthrough the secondary heat exchanger.
 10. The system of claim 1, furthercomprising a secondary heat exchanger that is adapted to receive thesupply water after it exits the first fluid side of the primary heatexchanger, wherein the secondary heat exchanger is adapted to decrease atemperature of the supply water as it flows through the secondary heatexchanger.
 11. The system of claim 9, further comprising: a first pumpthat is adapted to receive the supply water after it exits the firstfluid side of the primary heat exchanger; a pump water storage tank thatis adapted to receive the supply water from the first pump and store thesupply water in the pump water storage tank; and a second pump that isadapted to receive the supply water stored in the pump water storagetank and supply the supply water to the secondary heat exchanger. 12.The system of claim 11, further comprising a deionized water system thatis adapted to receive the supply water after it exits the secondary heatexchanger.
 13. A system comprising: a semiconductor fabrication facility(“fab”); a plurality of water-cooled processing tools positioned withinthe fab; a process cooling water loop that is dedicated to supplyingchilled water to the plurality of water-cooled processing tools, theprocess cooling water loop comprising a chilled water stream deliveredto the fab that flows to the plurality of water-cooled processing toolsand a returning water stream that is received from the plurality ofwater-cooled processing tools; and a primary heat exchanger comprising afirst fluid side and a second fluid side, the first fluid side beingadapted to receive supply water and the second fluid side being adaptedto receive at least a portion of the returning water stream, wherein theprimary heat exchanger is adapted to increase a temperature of thesupply water flowing in the first fluid side and decrease a temperatureof the returning water stream flowing in the second fluid side.
 14. Thesystem of claim 13, wherein the water stream delivered to the fab is ata first temperature and the returning water stream is at a secondtemperature, wherein the first temperature is less than the secondtemperature.
 15. The system of claim 14, wherein the supply water is ata first temperature where it enters the first fluid side and thereturning water is at a second temperature where it enters the secondfluid side, wherein the first temperature is less than the secondtemperature.
 16. The system of claim 13, further comprising: an incomingwater line in which supply water is adapted to flow; and at least onewater storage tank that is adapted to receive supply water from theincoming water line and store supply water, wherein the supply waterflowing in the first fluid side is received from at least one of theincoming water line or the at least one water storage tank.
 17. Thesystem of claim 16, further comprising: a first pump that is adapted toreceive the supply water after it exits the first fluid side of theprimary heat exchanger; a pump water storage tank that is adapted toreceive the supply water from the first pump and store the supply water;and a second pump that is adapted to receive the supply water stored inthe pump water storage take and supply the supply water to a secondaryheat exchanger, wherein the secondary heat exchanger is adapted toincrease a temperature of the supply water as it flows through thesecondary heat exchanger.
 18. The system of claim 17, further comprisinga deionized water system that is adapted to receive the supply waterafter it exits the secondary heat exchanger.